1、Designation: E 393 08Standard Test Method forMeasuring Reaction Rates by Analysis of Barium-140 FromFission Dosimeters1This standard is issued under the fixed designation E 393; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes two procedures for themeasurement of reaction rates by determining the amount ofthe
3、fission product140Ba produced by the non-threshold reac-tions235U(n,f),241Am(n,f), and239Pu(n,f), and by the thresholdreactions238U(n,f),237Np(n,f), and232Th(n,f).1.2 These reactions produce many fission products, amongwhich is140Ba, having a half-life of 12.752 days.140Ba emitsgamma rays of several
4、 energies; however, these are not easilydetected in the presence of other fission products. Competingactivity from other fission products requires that a chemicalseparation be employed or that the140Ba activity be determinedindirectly by counting its daughter product140La. This testmethod describes
5、both procedure (a), the nondestructive deter-mination of140Ba by the direct counting of140La several daysafter irradiation, and procedure (b), the chemical separation of140Ba and the subsequent counting of140Ba or its daughter140La.1.3 With suitable techniques, fission neutron fluence ratescan be me
6、asured in the range from 107n (neutrons) cm2s1to approximately 1015ncm2s1.1.4 The measurement of time-integrated reaction rates withfission dosimeters by140Ba analysis is limited by the half-lifeof140Ba to irradiation times up to about six weeks.1.5 The values stated in SI units are to be regarded a
7、sstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the
8、 applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 697 Test Methods for Chemical, Mass Spectrometric, andSpectrochemical Analysis of Nuclear-Grade PlutoniumDioxide Powders and PelletsD 1193 Specification for Reagent WaterE 170 Terminology Relating to
9、Radiation Measurementsand DosimetryE 181 Test Methods for Detector Calibration and Analysisof RadionuclidesE 261 Practice for Determining Neutron Fluence, FluenceRate, and Spectra by Radioactivation TechniquesE 704 Test Method for Measuring Reaction Rates by Ra-dioactivation of Uranium-238E 705 Test
10、 Method for Measuring Reaction Rates by Ra-dioactivation of Neptunium-237E 844 Guide for Sensor Set Design and Irradiation forReactor Surveillance, E 706(IIC)E 944 Guide for Application of Neutron Spectrum Adjust-ment Methods in Reactor Surveillance, E 706 (IIA)E 1005 Test Method forApplication andA
11、nalysis of Radio-metric Monitors for Reactor Vessel Surveillance, E706(IIIA)E 1018 Guide for Application of ASTM Evaluated CrossSection Data File, Matrix E 706 (IIB)3. Terminology3.1 Definitions:3.1.1 Refer to Terminology E 170.4. Summary of Test Method4.1 For nondestructive analysis, the fission do
12、simeter isallowed to cool for five days or more. The 1.596-MeV gammaenergy peak of140La, which is the daughter product of the140Ba, is then counted. This information, combined with thedecay constants for the La and the Ba, and the fission yield ofthe140Ba gives the reaction fission rate. When the pr
13、oper cross1This test method is under the jurisdiction ofASTM Committee E10 on NuclearTechnology and Applications and is the direct responsibility of SubcommitteeE10.05 on Nuclear Radiation Metrology.Current edition approved July 1, 2008. Published September 2008. Originallyapproved in 1984. Last pre
14、vious edition approved in 2002 as E 393 96 (2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright
15、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.section is used with the reaction rate, the equivalent fissionfluence rate can be determined.4.2 For destructive analysis, the fission product140Ba isseparated from the irradiated fission dosimete
16、r. The activity ofthe140Ba is determined by counting the 0.537 MeV gammaenergy peak. This information is then used as in 4.1 to give thereaction rate.5. Significance and Use5.1 Refer to Guide E 844 for the selection, irradiation, andquality control of neutron dosimeters.5.2 Refer to Practice E 261 f
17、or a general discussion of themeasurement of neutron fluence rate and fluence. The neutronspectrum must be known in order to measure neutron fluencerates with a single detector. Also it is noted that cross sectionsare continuously being reevaluated. The latest recommendedcross sections and details o
18、n how they can be obtained arediscussed in Guide E 1018.5.3 The reaction rate of a detector nuclide of known crosssection, when combined with information about the neutronspectrum, permits the determination of the magnitude of thefluence rate impinging on the detector. Furthermore, if resultsfrom ot
19、her detectors are available, the neutron spectrum can bedefined more accurately. The techniques for fluence rate andfluence determinations are explained in Practice E 261.5.4140Ba is a radioactive nuclide formed as a result ofuranium fission. Although it is formed in fission of any heavyatom, the re
20、lative yield will differ. Recommended fission yieldsfor140Ba production are given in Table 1. The direct (indepen-dent) fission yield of the daughter product140La, which iscounted, is given in Table 2. These independent fission yieldsare relatively low compared to the140Ba cumulative fissionyield an
21、d will not significantly affect the accuracy of thenondestructive procedure and need not be considered.5.5 The half-life of140Ba is 12.752 days. Its daughter140Lahas a half-life of 1.6781 days.3The comparatively longhalf-life of140Ba allows the counting to be delayed severalweeks after irradiation i
22、n a high-neutron field. However, toachieve maximum sensitivity the daughter product140Lashould be counted five to six days after the irradiation duringnondestructive analysis or five to six days after chemicalseparation if the latter technique is used.An alternative methodafter chemical separation i
23、s to count the140Ba directly.5.6 Because of its 12.752 day half-life and substantialfission yield,140Ba is useful for irradiation times up to aboutsix weeks in moderate intensity fields. The number of fissionsproduced should be approximately 109or greater for goodcounting statistics. Also, if the ir
24、radiation time is substantiallylonger than six weeks, the neutron fluence rate determined willapply mainly to the neutron field existing during the latter partof the irradiation. The140Ba decay constant and yield areknown more accurately than those of many fission products, soit is sometimes used as
25、 a standard or base reaction with whichother measurements can be normalized.6. Apparatus6.1 For nondestructive analysis the chemical separationequipment, materials, and reagents are not required.6.2 A NaI(Tl) or Germanium Gamma-Ray Spectrometer, seeTest Methods E 181 and E 1005.6.3 Balance, providin
26、g the accuracy and precision requiredby the experiment.6.4 Centrifuge, clinical type, accommodating 50-mL centri-fuge tubes.6.5 Steam Bath.6.6 Ice Bath.6.7 Drying Oven.6.8 Filter Cones.6.9 Fiberglass Filter Circles for filter cone.6.10 Centrifuge Tubes, 50-mL capacity.6.11 Fine Sintered-Glass Crucib
27、les.7. Reagents and Materials7.1 Purity of Fission DosimetersHigh purity uraniumplutonium, neptunium, and thorium in the form of alloy wire,foil, or oxide powder are available.7.1.1 Target material shall be furnished with a certificate ofanalysis indicating any impurity concentrations.3Nuclear Walle
28、t Cards, compiled by J. K. Tuli, National Nuclear Data Center,April 2005.TABLE 1 Recommended Cumulative Fission Yields for140BaProductionFission DosimeterThermal or FastNeutron FieldFission Yield,%A,B235UTF6.21448 6 1%5.977730 6 1%238U F 5.815236 1%239Pu TF5.354516 1.4 %5.32323 6 1.4 %237Np F 5.4884
29、8 6 2%232Th F 7.87767 6 2.8 %241Am TF5.92114 6 2.8 %4.92101 6 4%AThese ENDF/B-VI values are considered the best available data. The uncer-tainties are expressed as a percentage of the fission yield.BSpecial Issue on Evaluated Nuclear Data File ENDF/B-VII.0,” Nuclear DataSheets, J. K. Tuli Editor, Vo
30、l. 107, December 2006. Data available on theENDF/BVII web site at URL: http:/www.nndc.bnl.gov/exfor/endf00.htm.TABLE 2 Independent Fission Yields for140La ProductionFission DosimeterThermal or FastNeutron FieldFission Yield, %A,B235UTF5.25630 3 1036 64 %2.03998 3 1036 64 %238U F 2.48002 3 1056 64 %2
31、39Pu TF1.01969 3 1026 64 %9.86983 3 1036 64 %237Np F 5.121 3 1036 64 %232Th F 4.84989 3 1066 64 %241Am TF1.5295 3 1026 64 %2.0392 3 1026 32 %AThese ENDF/B-VI values are considered the best available data. The uncer-tainties are expressed as a percentage of the fission yield.B“Special Issue on Evalua
32、ted Nuclear Data File ENDF/B-VII.0,” Nuclear DataSheets, J. K. Tuli, Editor, Vol. 107, December 2006.E3930827.1.2 Fission dosimeters shall be encapsulated in hermeti-cally sealed containers to avoid loss of materials and forhealth-hazard requirements.47.1.3 In thermal reactors threshold reaction dos
33、imeters (forexample,238U,237Np,232Th) shall be shielded from thermalneutrons with elemental, or compounds of, cadmium, gado-linium, or boron to prevent fission production from tracequantities (40 ppm) of235U, and239Pu and to suppressbuildup of interfering fissionable nuclides, for example,239Puin th
34、e238U dosimeter,238Np and238Pu in the237Np dosimeter,and233Uinthe232Th dosimeter (see Guide E 844).7.2 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical
35、Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.3 Purity of WaterUnless otherwise indicat
36、ed, referencesto water shall be understood to mean reagent water as definedby Type II of Specification D 1193.7.4 Acetic Acid (36 %)Dilute 360 mL of glacial aceticacid to 1 L with water.7.5 Acetic Acid (6 %)Dilute 60 mL of glacial acetic acidto 1 L with water.7.6 Ammonium Acetate Solution (231 g/L)D
37、issolve 231 gof ammonium acetate in water and dilute to 1 L.7.7 Ammonium Hydroxide (sp gr 0.90)Concentrated am-monium hydroxide (NH4OH).7.8 Barium Carrier (10 mg Ba/mL)See Section 8.7.9 Ethyl Alcohol (95 %).7.10 Hydrochloric Acid (sp gr 1.42)Concentrated hydro-chloric acid (HCl).7.11 Iron Carrier (1
38、0 mg Fe+/mL)Dissolve 48.4 g ofFeCl36H2O in 100 mL of water and dilute to 1 L with water.7.12 Nitric Acid, Fuming.7.13 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).7.14 Sodium Carbonate SolutionPrepare a saturated so-lution of sodium carbonate (Na2CO3).7.15 Sodium Chromate Solution (243 g/L
39、)Dissolve 243 gof sodium chromate (Na2CrO4) in water and dilute to 1 L.7.16 Strontium Holdback Carrier (10 mg Sr/mL)Dissolve24.2 g of Sr(NO3)2in 1 L of water. Mix well, filter through aglass wool, and store in a polyethylene bottle.7.17 Hydrofluoric Acid (HF) (1 N).8. Preparation and Standardization
40、 of Barium Carrier8.1 Preparation and Standardization of Barium Carrier:8.1.1 Dissolve 19.0 g of barium nitrate (Ba(NO3)2)indeionized water and dilute to 1 L. Filter through glass wool andstore in a polyethylene bottle.8.2 Standardization of Barium Carrier:8.2.1 Pipet 5.0 mL of the carrier solution
41、into a 250-mLbeaker and dilute to approximately 100 mL.Add 5 mLof aceticacid (36 %) and 10 mLof ammonium acetate solution. Bring toboiling; add 5 mL of Na2CrO4solution dropwise with stirring;boil for 1 min with stirring. Cool the mixture to roomtemperature and filter the precipitated barium chromate
42、(BaCrO4) through a fine preweighed sintered-glass crucible.8.2.2 Wash the precipitate three times with 5-mLportions ofdeionized water and three times with 5-mL portions of ethylalcohol. Dry at 110C, cool, and weigh. Calculate the bariumcontent as follows:Ba11, mg/mL 5 W/V! 3 0.5421 (1)where:W = mill
43、igrams of BaCrO4, andV = millilitres of carrier used.9. Procedure for Nondestructive Analysis9.1 Decide on the size and shape of sample to be irradiated(see Guide E 844).9.2 Weigh the sample to the accuracy and precision of theexperiment.9.3 Place the sample in a cadmium, gadolinium, or boroncover i
44、f desired (see Guide E 844). Seal into a capsule whenrequired by safety considerations.9.4 Irradiate the sample for a predetermined period of time.Record the beginning and end of the irradiation period. Takeinto account any reactor power variation during the exposureperiod.9.5 Prior to counting, rem
45、ove any covering material fromthe dosimeter if it possesses interfering radionuclides. Ifencapsulated in quartz, copper, aluminum, or vanadium, theencapsulating material need not be removed before counting.9.6 After five days after the irradiation, count the140Ladirectly on a gamma-ray spectrometer
46、(1.596-MeV gamma), orby coincidence counting.6Waiting exactly five days beforecounting is not required, but the140La is at its maximum about134 h after the irradiation.10. Procedure for Radiochemical Analysis10.1 Decide on the size and shape of sample to be irradiated(see Guide E 844).10.2 Weigh the
47、 sample to the accuracy and precision of theexperiment.10.3 Place the sample in a cadmium, gadolinium, or boroncover if desired (see Guide E 844). Seal into a capsule whenrequired by safety considerations.10.4 Irradiate the sample for a predetermined period of time.Record the beginning and end of th
48、e irradiation period. Takeinto account any reactor power variation during the exposure4Vanadium-encapsulated monitors of high purity are available from IsotopeSales Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830.5“Reagent Chemicals,American Chemical Society Specifications,”Am. Chemi-ca
49、l Soc., Washington DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Society, see “Reagent Chemicals and Standards,” by JosephRosin, D. Van Nostrand Co., Inc., New York, NY, and the “United StatesPharmacopeia.”6Dierckx, R., Maracci, G., and Rustichelli, F., “Measurement of the La-140Fission Product Yield for Fissions in U-238 in a Thermal Reactor Type Spectrum,”Journal of Nuclear Energy, Vol 25, pp. 8589, 1971.E393083period. Since the fission product to be extracted,140Ba, has a12.752-day half-life, there can be
